Conventional flat plate solar collectors are shown, for example, in U.S. Pat. No. 2,680,437. Some improvements have been made on this type of solar heat trap, but they have primarily consisted of altering the configuration of the absorber (collector plate) surface, as for example in U.S. Pat. No. 4,029,080, in an attempt to increase area and to gain longer efficient exposure to existing solar radiation during a normal day.
As pointed out in U.S. Pat. No. 4,119,083, "in the past solar energy absorbing materials have largely been imperforate metal plates coated with highly absorptive coatings."
Apparently, no one has specifically addressed the issue of both increased effective heat transfer surface of the solar collector plate and the issue of practical and inexpensive manufacture of such plate. A desired object of the present invention is to both maximize heat transfer and to maintain inexpensive manufacturing design requirements.